OVERALL OBJECTIVES ARE: 1) To define the mechanisms which regulate protein turnover in intestinal mucosa. 2) To begin the study of synthesis of specific intestinal proteins, using organ culture as a model. Presently projected studies include: a) Study of the role of pancreatic and lysosomal proteases using the developing intestine as a model. b) Isolation and characterization of soluble alkaline phosphatase from suckling rat, and study of its biosynthesis. c) Biosynthesis of apoprotein B in organ culture. d) Purification of intrinsic factor receptor proteins. 3) To study the relationship between structure and function of intrinsic factor receptor proteins.